Sampling/Quantization Converters

摘要

Provided are, among other things, systems, apparatuses, methods and techniques for converting a continuous-time, continuously variable signal into a sampled and quantized signal. One such apparatus includes an input line for accepting an input signal that is continuous in time and continuously variable, multiple processing branches coupled to the input line, and an adder coupled to outputs of the processing branches, with each of the processing branches including a bandpass noise-shaping circuit, a sampling/quantization circuit coupled to an output of the bandpass noise-shaping circuit, a digital bandpass filter coupled to an output of the sampling/quantization circuit, and a line coupling an output of the sampling/quantization converter circuit back into the bandpass noise-shaping circuit. A center frequency of the digital bandpass filter in each processing branch corresponds to a stopband region in a quantization noise transfer function for the bandpass noise-shaping circuit in the same processing branch.

主权项

1. An apparatus for converting a continuous-time, continuously variable signal into a sampled and quantized signal, comprising:
an input line for accepting an input signal that is continuous in time and continuously variable; a plurality of processing branches coupled to the input line, each of said processing branches including: (a) a bandpass noise-shaping circuit, (b) a sampling/quantization circuit coupled to an output of the bandpass noise-shaping circuit, (c) a digital bandpass filter coupled to an output of the sampling/quantization circuit, and (d) a line coupling the output of the sampling/quantization circuit back into the bandpass noise-shaping circuit; and an adder coupled to outputs of the plurality of processing branches, wherein a center frequency of the digital bandpass filter in each said processing branch corresponds to a stopband region in a quantization noise transfer function for the bandpass noise-shaping circuit in the same processing branch, wherein each of said digital bandpass filters includes: (a) a quadrature frequency downconverter that has in-phase and quadrature outputs, (b) a first lowpass filter coupled to the in-phase output of the quadrature frequency downconverter, (c) a second lowpass filter coupled to the quadrature output of the quadrature frequency downconverter, and (d) a quadrature frequency upconverter coupled to outputs of the first and second lowpass filters, and wherein a frequency response of each of said first and second lowpass filters has a magnitude that varies approximately with frequency according to a product of raised sin(x)/x functions.